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Downspout Drainage Pipe Installation Tips

Frequently I see builders install downspout drain lines close to the foundation of a new house. They do this long before the backfill dirt around your house has compacted. This is a mistake.

Piping installed in uncompacted ground will often develop negative pitch. This means that the pipe drains the wrong way! In many cases, the stress on the pipe caused by compacting soil actually fractures the pipes or cause joints to leak. This is unacceptable.

The better choice is to install this piping in virgin soil which was undisturbed by the original foundation excavation. This may mean staying 5 or 6 feet away from the foundation. What a small price to pay for long term peace of mind!

Always try to lay the pipe in a bed of sand or gravel. Don't allow an underground pipe to act as a beam. If a pipe has a hollow spot beneath it, it will become a beam just as soon as dirt is piled on top of it. The weight of the dirt (often 100 lbs per cubic foot!) will cause the pipe to bend or break.

If your soil is rocky, be sure to cover the downspout drain pipes with sand or smooth gravel. Sharp rocks can crack piping materials.

How Deep are They Buried?

Downspout drain lines do not have to be deeply buried. In fact, if your lot is fairly level, you must be very careful as to how deep they are installed. If you go too deep, the pipe may still be underground when you get to the discharge point!

Think about starting the installation at the point where the pipe will discharge. Work backwards towards your house. Keep in mind that you may have to pass under sidewalks or driveways. Never install a "trap" in a downspout drain line. A trap is a low spot where water or solid particles can collect. The solid particles may eventually clog the pipe. If you live in a cold climate, trapped water may freeze and burst the pipe.

In many instances, I would dig a trench only 16 inches deep. This trench would follow the natural contour of the ground. A trench this deep allows you to have a foot of dirt over the pipe in many locations. Trenching machines work great! Set the depth and it follows the contour of the ground for you. Watch out for buried electric lines! ZOT!

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2 Responses to Downspout Drainage Pipe Installation Tips

I have installed a french drain in my brick planter, which is 12" wide X36" deep and 16 Ft long. It all works good, except for one small area.
this area is where my watering line comes up from the ground to a mini sprinkler system. At this point, the water seeps thru the soil down to the ground below, and saturates it. Could I put gravel on the ground where the water settles, or would that not help.
Thank you